12:25 PM | **Flash flooding to become an increasing concern with more significant rainfall on the way**
Paul Dorian
Overview
The grounds are already well saturated in the DC-to-Philly-to-NYC corridor after recent soaking rains and there is more significant rainfall on the way. As a result, localized flash flooding will become an increasing concern over the next few days as we’ll continue to get hit by rounds of showers and thunderstorms. In fact, many spots in the I-95 corridor may receive 3-5 inches of rain between this afternoon and Saturday night and this is on top of all of the recent rainfall.
Mid-day look at the radar with numerous batches of rain in the eastern third of the nation; courtesy NOAA, College of DuPage
Discussion
The frontal system that moved through last night remains in very close proximity and it will remain relatively stationary going into the weekend. In addition to this boundary zone, deep tropical moisture continues to push northward along the eastern seaboard aided by a very slow-moving sub-tropical low over the northeast Gulf of Mexico and Bermuda high pressure over the western Atlantic. Current radar is showing multiple batches of rain throughout the eastern third of the nation and we’ll experience rounds of showers and thunderstorms later today, tonight and tomorrow.
12Z NAM forecast map of total rainfall amounts between now and Saturday 8PM; courtesy NOAA/EMC, tropicaltidbits.com
The setup for late tomorrow night, Friday and Friday night is especially ominous-looking in terms of excessive rainfall potential as the combination of cold, high pressure to the north, deep tropical moisture to our south and the same stationary frontal boundary zone in between may very well result in steady, heavy rainfall for much of the I-95 corridor. That front finally lifts to the north as a warm front on Saturday and then another cold front passes through the region on Sunday keeping us unsettled as we begin the new week. There is some hope that Sunday and Monday may feature some sunshine and perhaps less of a chance for rain compared to the next few days which look very wet indeed.
Meteorologist Paul Dorian
Vencore, Inc.
vencoreweather.com
Extended morning video discussion on the excessive rainfall and flash flooding threat: